Audio drivers, commonly referred to as speakers or speaker modules, are known to create sound by actuating a voice coil, which can be accomplished by passing electrical current through the voice coil such that the voice coil becomes an electromagnet. Further, the electrical current can be driven in opposite directions, creating an electromagnet that changes magnetic polarity. The electromagnet is attracted to the permanent magnet (when the electromagnet includes the opposite polarity as that of the permanent magnet) and alternatively repelled by the permanent magnet (when the electromagnet includes the same polarity as that of the permanent magnet). Based on the flow of electrical current, the voice coil may actuate.
However, some of the electrical energy input into the audio driver in the form of electrical current is converted to thermal energy. As the thermal energy increases, the performance (sound quality) of the audio driver decreases, particularly when the audio driver is enclosed. For example, an audio driver enclosed in a metal enclosure of a portable electronic device may generate heat under continuous use causing the resistance of the voice coil to increase. As a result, the amount of electrical current delivered to the voice coil is reduced. This not only reduces performance of the audio driver but also reduces efficiency. Regarding the latter, additional electrical current may be required to regain the performance, but this can draw additional electrical power stored in a battery of the portable electronic device.
One method for offsetting these undesired effects is to provide an audio driver with a specialized magnet having a relatively high thermal capacity and configured to absorb the additional heat. However, these specialized magnets are generally more expensive than traditional magnets. Accordingly, additional costs associated with these specialized magnets increase the overall cost of the portable electronic device.